Members of this superfamily are widespread throughout the world. They are primarily
parasites of herbivores such as ruminants and horses although a few species are found in
ratite birds and marsupials.
They have the following general
They are large-bodied worms and
are easily seen in situ at necropsy of infected hosts.
Males have a copulatory bursa
Most have large mouth openings and
prominent buccal capsules which may contain teeth
in some species. They use their buccal capsules in feeding, either by grazing the
mucosal surface or by attaching to a plug of
mucosa, drawing it into the buccal capsule and digesting it.
Leaf crowns may
be present as accessory cuticular structures around the opening of the buccal capsule.
Most females of this group pass strongyle-type
Some species have life cycles that include extensive migrations
through the bodies of their hosts. They include the large strongyles of equines (e.g. Strongylus vulgaris), the gape worm of birds (Syngamus trachea) and the kidney worm of swine (Stephanurus dentatus).
Most have direct life cycles with infection by ingestion of
infective third stage larvae but a few such as Stephanurus dentatus (the
swine kidney worm) and Syngamus trachea (the gapeworm of fowl) may include
earthworms as transport hosts.
Most are found in the large intestine but a few species occur in
the respiratory and urinary tracts.
Three families are important in domestic animals - Strongylidae, Chabertiidae and Syngamidae
Members of this family are common in equines but they are also found in elephants,
ostriches, rhinoceros, tapirs, tortoises, warthogs and marsupials. Their predilection
sites include primarily the cecum and colon. The preparasitic phases of the life cycles
are similar with strongyle-type eggs passing in the feces of infected hosts. Development
to the infective, ensheathed third stage larvae may take as little as 7-10 days in a warm,
Equine strongylids are usually divided into the large strongyles, belonging to the
subfamily Strongylinae and the small strongyles which are members of the
This family has been further subdivided into two subfamilies - the Chabertiinae and the
The Chabertiinae are often called the bowel worms because of their
location in the colon of their hosts. They have a prominent bell-shaped buccal capsule.
The Oesophagostominae are often called the nodular worms because their
parasitic larvae provoke nodule formation in the intestines of their definitive hosts.
Adults are found in the colon and are common in pigs, ruminants, primates and rodents.
The table below lists the species of this family commonly found in domestic and wild
||North American beaver
||Camels, cattle, chamois, deer, gazelles, goats, sheep
||African and Asian non-human primates
||Sheep, goats, alpaca, antelope (African)
||Cattle, zebra, water buffalo
||Ruminants - primarily sheep and goats